JP2007129154A - Treatment liquid and treatment method of soft magnetism green compact, magnetic powder and soft magnetic material, and motor using the green compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a green compact composed of magnetic powders with heat resistant insulating films, and powder magnetic cores having high specific resistance and low iron loss. <P>SOLUTION: This green compact composed of magnetic powders has an insulating film formed at the surface of alloy powders whose main constituents are iron powders or iron. This green compact also depends on the powder magnetic cores, magnetic powders for obtaining the magnetic cores, and their treatment liquid. As the characteristics of the above powder magnetic cores, density is 7.5 g/cm<SP>3</SP>or higher, average grain diameter of these magnetic powders is 30 to 200 μm, the average thickness of the insulating film is 1 to 700 nm, hysteresis loss Wh<SB>1T/400 Hz</SB>is 45 W/kg or lower; a specific resistance is 1,000 μΩ cm or higher, eddy current loss We<SB>1T/400 Hz</SB>is 510 W/kg or lower, and iron loss W<SB>1T/400 Hz</SB>is 50 W/kg or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a soft magnetic green compact, a processing liquid and processing method for magnetic powder and soft magnetic material, and a motor using the green compact.

The dust cores used for the above applications are required to have low iron loss and high magnetic flux density as well as their magnetic properties do not deteriorate even in the low to high frequency region. . Iron loss includes eddy current loss, which has a large relationship with the specific resistance of the magnetic core, and hysteresis loss, which is affected by distortion in the iron powder resulting from the iron powder manufacturing process and the subsequent process history. The iron loss (W) can be represented by the sum of eddy current loss (We) and hysteresis loss (Wh) as shown below (Formula 1). In (Expression 1), f is a frequency, Bm is an exciting magnetic flux density, ρ is a specific resistance, t is a thickness of the material, and k ₁ and k ₂ are coefficients.
W = We + Wh = (k ₁ Bm ² t ² / ρ) f ² + k ₂ Bm ^1.6 f (Equation 1)
From (Equation 1), since the eddy current loss (We) increases in proportion to the square of the frequency f, it is indispensable to suppress the eddy current loss (We) particularly in order not to deteriorate the magnetic characteristics at high frequencies. It is. In order to suppress the generation of eddy currents in the dust core, it is necessary to reduce the size of the magnet powder to be used, and to form an insulating film on the surface of each magnet powder, and to use a dust core that is compression-molded using the magnet powder There is.

  In such a dust core, if the insulation is insufficient, the specific resistance ρ is reduced, and the eddy current loss (We) is increased. On the other hand, when the insulating film is thickened to increase the insulation, the volume ratio of the soft magnetic powder in the magnetic core is reduced, and the magnetic flux density is reduced. Also, in order to improve the magnetic flux density, if the density of the soft magnetic powder is increased by compressing the soft magnetic powder at a high pressure, the distortion of the soft magnetic powder during molding cannot be avoided, and the hysteresis loss (Wh) As a result, it is difficult to suppress iron loss (W). In particular, since the eddy current loss (We) is small in the low frequency region, the influence of the hysteresis loss (Wh) in the iron loss (W) becomes large.

  As a conventional method for producing a dust core, there is a method (Patent Document 1) in which soft magnetic powder and insulating particles are mixed to form an insulating layer on the surface of the soft magnetic powder particles. Further, a method (Patent Document 2) is known in which a powder magnetic core is manufactured by compression molding after mixing a resin as a binder with soft magnetic powder on which an insulating layer is formed.

JP 2003-332116 A JP 2004-288893 A

  However, the above-described manufacturing method has a drawback that eddy current loss (We) increases if insulation by the insulating layer is insufficient. In order to improve the insulation, it is conceivable to increase the thickness of the insulating layer. However, as the insulating layer becomes thicker, the space factor of the soft magnetic powder decreases, and the magnetic flux density decreases as described above. In addition, when compression molding is performed at a high pressure in order to increase the density in order to improve the magnetic flux density, the formed insulating layer is destroyed and eddy current loss (We) increases, or during molding that remains in the soft magnetic powder Since the distortion of the steel increases and the hysteresis loss (Wh) increases, the iron loss (W) finally increases.

  On the other hand, a highly reliable insulating layer is usually an inorganic substance, and since the inorganic substance has a high hardness, the magnetic core formed by compression molding using magnetic powder having the inorganic insulating layer formed on the surface of the magnetic powder has a high porosity, and the magnetic flux density of the magnetic core decreases. Easy to do. At that time, if the compression molding pressure is increased to increase the density of the soft magnetic powder in the magnetic core, the distortion of the magnetic powder at the time of molding increases and the hysteresis loss (Wh) increases. ) Becomes difficult to control. In particular, since the eddy current loss (We) is small in the low frequency region, the influence of the hysteresis loss (Wh) in the iron loss (W) becomes large. Therefore, it is indispensable for the magnetic core used in a wide frequency band to reduce both eddy current loss (We) and hysteresis loss (Wh). However, as for the reduction of the hysteresis loss (Wh), it is difficult to take measures to improve the heat resistance of the insulating layer, and there is no good solution at present.

  The present invention improves the magnetic flux density by increasing the space factor of the soft magnetic powder, improves the coating with the insulating layer on the surface of the soft magnetic powder, suppresses eddy current loss (We), and reduces the soft magnetic powder. An object of the present invention is to provide a soft magnetic powder for a dust core in which hysteresis loss (Wh) due to compression residual strain therein is suppressed. It is another object of the present invention to provide a powder molded body obtained by using the same, a processing solution for forming an insulating layer of magnetic powder, a magnetic powder formed using the magnetic powder formed with the insulating layer, and a method for producing the same. And

  In order to solve the above problems, the present invention provides a dust core having a high density, a high resistance value, and excellent magnetic properties, and a magnetic powder suitable for obtaining the dust core.

A dust core according to the present invention is a powder compact of magnetic powder having an insulating film formed on the surface of iron powder or an alloy powder containing iron as a main component, and has a density of 7.5 g / cm ³ or more. The average particle diameter of the magnetic powder is 30 to 200 μm, the average thickness of the insulating film is 1 to 700 nm, substantially no residual stress is observed, and the hysteresis loss Wh _{1T / 400 Hz} is 45 W / kg or less, specific resistance is 1000 μΩ · cm or more, eddy current loss We _{1T / 400 Hz} is 510 W / kg or less, and iron loss W _{1T / 400 Hz} is 50 W / kg or less. is there.

The magnetic powder according to the present invention is a magnetic powder having an insulating film formed on the surface of an iron powder or an alloy powder containing iron as a main component, and the average particle size of the magnetic powder is 30 to 200 μm. The hysteresis loss Wh _{1T / 400 Hz} is 45 W / kg or less when a green compact having an average thickness of 1 to 700 nm and a density of 7.5 g / cm ³ is manufactured. The resistance is 1000 μΩ · cm or less, the eddy current loss We _{1T / 400 Hz} is 10 W / kg or less, and the iron loss W _{1T / 400 Hz} is 50 W / kg or less. . This magnetic powder is suitable for obtaining the powder magnetic core.

  The above magnetic characteristics are shown based on the magnetic characteristics when the powder compact is annealed at 600 ° C., which is considered to be the most standard for producing a dust core. Therefore, if the annealing temperature changes, the magnetic characteristics can naturally change, but the present invention naturally does not exclude them. For example, according to the data of the examples of the present invention shown in Table 1, as the annealing temperature increases to 700 ° C., 800 ° C., and 900 ° C., the hysteresis loss tends to decrease, and the specific resistance is the same. Eddy current loss and iron loss tend to increase slightly with increasing temperature. However, if the characteristics at 600 ° C. satisfy the above characteristics, the object of the present invention can be achieved. Therefore, it is within the scope of the present invention.

In the present invention, the residual stress of the powder magnetic core (fired body) obtained by annealing at 600 ° C. when the magnetic powder insulating film is 3 to 500 nm is substantially not observed, and the hysteresis loss Wh _{1T / 400 Hz} is 45 _W. It is desirable that the specific resistance is 1000 to 5000 μΩ · cm, the eddy current loss We _{1T / 400 Hz} is 510 W / kg or less, and the iron loss W _{1T / 400 Hz} is 4550 W / kg or less.

  The insulating layer forming treatment liquid for soft magnetic powder for dust core according to the present invention contains at least one selected from alkoxysilane and derivatives thereof, and alcohol and water.

  According to the present invention, it is possible to obtain a high-density powder compact having high heat resistance and high specific resistance, a magnetic powder capable of obtaining it, and a treatment agent suitable for producing the magnetic powder.

  First, the difference between the magnetic powder and the known magnetic powder in the present invention will be described with reference to the drawings. FIG. 4 schematically shows a cross-sectional structure of a dust core according to the present invention, and 5 is a magnetic powder 5 having an insulating coating 6. FIG. 1 schematically shows a cross-sectional structure of a magnetic powder according to the present invention, in which an insulating film 2 such as an oxide is formed on the surface of powder particles 1 of iron or an alloy mainly composed of iron. Yes. The average particle size of the insulating magnetic powder is preferably 30 to 200 μm, more preferably 40 to 100 μm. The insulating film 2 is substantially continuous when the magnetic powder is manufactured. The reason for this is that the metal powder (soft magnetic powder) is treated in a treatment liquid, which will be described later, so to take a wet method. However, when this magnetic powder is molded and annealed, as shown in FIG. 2, the insulating film 2 ′ is cracked due to the difference in thermal expansion coefficient between the metal powder and the insulating film, and the insulating film is compared with the insulating film of FIG. The continuity or coverage is reduced.

  The average thickness of the insulating films 2 and 2 ′ in FIGS. 1 and 2 is 1 to 700 nm, preferably 30 to 200 nm, and particularly preferably 40 to 100 nm. The thickness of the insulating film can be adjusted by the processing time, temperature, composition of the processing solution, and the like.

  However, unlike the case where the insulating particles 4 by the known method of FIG. 3 are attached to the metal particles 3, the magnetic powder of the present invention has substantially the continuity of the insulating film, and therefore the resistance value becomes high. . Further, since the continuity or coverage of the insulating film is far superior to that of FIG. 3, the leakage magnetic flux is small and the magnetic characteristics of the dust core are excellent.

  The structure of the magnetic powder of FIG. 3 is based on the method described in Patent Document 1, and the metal powder 3 and the oxide particles 4 are mixed by a so-called dry method, and the oxide particles are adhered to the surface of the metal powder particles. Therefore, the continuity of the insulating film is clearly inferior to that of the magnetic powder of the present invention.

  Patent Document 2 discloses a technique in which a silicone resin is coated on metal particles and heat-treated. However, since the carbon content of the silicone resin diffuses into the magnetic powder particles, the magnetic properties of the magnetic powder deteriorate. There is a concern to do. The treatment liquid suitable for the present invention does not have such a problem. Moreover, although there is a problem that the heat resistance of the insulating coating obtained by processing with a known phosphoric acid component-containing liquid is low, the insulating film obtained using the processing liquid of the present invention has heat resistance, and therefore has a sufficiently high temperature. Therefore, the magnetic properties of the dust core are excellent.

The magnetic powder of the present invention is a soft magnetic powder particle whose surface is insulation-coated with an insulating layer made of an inorganic material that does not contain a resin, and the soft magnetic powder particle has no compressive residual strain. The powder magnetic core having the above-described configuration is composed only of soft magnetic powder particles whose surface is insulation-coated with an insulating layer having an average thickness of 1 to 700 nm that is made of an inorganic material that does not contain a resin. Therefore, the insulating property of the insulating layer is high, and as a result, the space factor of the soft magnetic powder can be increased, the magnetic flux density can be improved, and the eddy current loss (We) can be kept small. In addition, since the insulating layer is made of SiO ₂ having heat resistance of 600 ° C. or higher, the powder magnetic core having the above-described configuration can be annealed at a temperature of 600 ° C. or higher, and the compression residual strain of the soft magnetic powder can be reduced. Is possible. Furthermore, the hysteresis loss (Wh) can be kept small, and as a result, the iron loss (W) kept extremely low can be realized.

  Here, the dust core has a density ratio of 95% or more and a space factor of the soft magnetic powder in the dust core of 90% or more in order to surely obtain desired magnetic characteristics. Desirably, a saturation magnetic flux density of about 1.8 to 1.9 T (tesla) of a silicon steel plate that has been frequently used so far can be obtained. The space factor in this case is the space factor of the soft magnetic powder itself excluding the insulating layer.

The average thickness of SiO ₂ that is the insulating layer on the surface of the soft magnetic powder is preferably 1 to 700 nm. When the insulating layer has a thickness of 1 nm or less, a tunnel current is generated and the insulating property is lowered. On the other hand, when the insulating layer is 700 nm, the space factor of SiO _{2 in} the dust core cannot be ignored, and it is difficult to increase the density of the soft magnetic powder by compression molding for the soft magnetic powder having a hard insulating layer on the surface. As a result, a high magnetic flux density cannot be obtained.

In the case the mechanical strength is required for the dust _{core, SiO 2 Na 2 O / SiO} 2 based water glass or dissolved in water can be used as the inorganic binder to the surface of the soft magnetic powder after surface treatment with A surface treatment using a phosphoric acid / boric acid / magnesia-based solution may be performed, and annealing may be performed after compression molding. The inorganic binder softens during annealing at a temperature of 600 ° C. or higher, the inorganic binder material wets and spreads on the surface of the soft magnetic powder after the surface treatment with SiO ₂ , and the inorganic binder material solidifies after completion of annealing, The strength of the dust core is ensured. In that case, the volume fraction in the powder magnetic core of the solidified inorganic binder material needs to be 3 vol% or less in order to ensure magnetic characteristics.

  Since the dust core of the present invention is a core intended for low iron loss, it is desirable that the soft magnetic powder used has an average particle size of 30 to 200 μm. Although depending on the frequency region in which the dust core is used, when the average particle size of the soft magnetic powder is larger than 200 μm, the value of the intragranular eddy current generated in the soft magnetic powder increases. On the other hand, if the average particle size of the soft magnetic powder is smaller than 30 μm, the thickness of the insulating layer relative to the soft magnetic powder cannot be ignored, and it becomes difficult to reduce the space factor of the insulating layer in the dust core, A high insulating layer significantly reduces the compressibility of the soft magnetic powder, making it impossible to obtain a high magnetic flux density.

  A representative embodiment of the present invention is as follows. An insulating layer forming treatment liquid for forming an insulating layer on the surface of the soft magnetic powder for dust core contains at least one of alkoxysilane and its derivatives, and contains alcohol and water, and further, if necessary, a hydrolysis catalyst. An insulating layer forming treatment liquid of soft magnetic powder for a dust core characterized by comprising:

  The present invention also provides a method for forming an insulating layer of a soft magnetic powder for a dust core, wherein an insulating layer is formed on the surface of the soft magnetic powder. That is, the insulating layer forming treatment liquid contains at least one of alkoxysilane and derivatives thereof, alcohol and water, and further, if necessary, a hydrolysis catalyst, and the soft magnetic powder is mixed with the insulating layer forming treatment liquid, An insulating layer having an average thickness of 1 to 700 nm can be formed by heat treatment at a temperature. As described above, the alkoxysilane derivative includes a hydrolysis product of alkoxysilane, a dehydration condensate thereof, and alkoxysiloxane.

  Also, an insulating layer forming treatment solution for soft magnetic powder for dust cores that forms an insulating layer on the surface of soft magnetic powder is used for at least one of alkoxysilane and its derivatives, alcohol and water, and if necessary, for hydrolysis. It contains a catalyst. Thereby, an insulating layer having an average thickness of 1 to 700 nm can be formed by mixing an insulating layer forming treatment liquid with the soft magnetic powder and performing a heat treatment at a predetermined temperature.

  A powder magnetic core formed by pressing using a soft magnetic powder for a powder magnetic core having an insulating layer having an insulating layer with an average thickness of 1 to 700 nm on the surface is subjected to heat treatment at 600 to 900 ° C., thereby causing iron loss, particularly Hysteresis loss can be reduced. The dust core of the present invention is used for motor cores requiring higher magnetic flux density, solenoid cores (fixed cores) for solenoid valves incorporated in electronically controlled fuel injection devices of diesel engines and gasoline engines, plungers, and other various actuators. It can be applied as a core part.

  The general formulas of alkoxysiloxane and alkoxysilane in the insulating layer forming treatment liquid are represented by (Formula 1) and (Formula 2), respectively, and examples thereof include compounds having an alkoxy group in the terminal group and side chain as shown.

また、溶媒のアルコールにはアルコキシシロキサン、アルコキシシラン中のアルコキシ基と同じ骨格の化合物が好ましいがこれらに限られるものではない。具体的にはメタノール、エタノール、プロパノール、イソプロパノール等が挙げられる。

Further, the alcohol of the solvent is preferably a compound having the same skeleton as the alkoxy group in alkoxysiloxane or alkoxysilane, but is not limited thereto. Specific examples include methanol, ethanol, propanol, isopropanol and the like.

  Further, the catalyst for hydrolysis and dehydration condensation may be any of an acid catalyst, a base catalyst, and a neutral catalyst, but the neutral catalyst is most preferable because corrosion of the metal can be minimized. As the neutral catalyst, an organotin catalyst is effective. Specifically, bis (2-ethylhexanoate) tin, n-butyltris (2-ethylhexanoate) tin, di-n-butylbis (2-ethyl) Hexanoate) tin, di-n-butyl bis (2,4-pentanedionate) tin, di-n-butyl dilauryl tin, dimethyl dineodecanoate tin, dioctyl dilarylate tin, dioctyl dineodecano Examples include, but are not limited to, ate tin. Examples of the acid catalyst include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, formic acid, acetic acid, and the like, and examples of the base catalyst include sodium hydroxide, potassium hydroxide, aqueous ammonia, and the like, but are not limited thereto.

  The total content of alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and dehydration condensate thereof in the insulating layer forming treatment liquid is preferably 0.2 to 60 vol%. When the total content of alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and dehydration condensate thereof is 0.2 vol% or less, it becomes difficult to control the amount of water added to alkoxysiloxane and alkoxysilane during hydrolysis. That is, the amount of water in the alcohol and the amount of water mixed during the insulating layer formation process cannot be ignored with respect to the water in the treatment liquid. On the other hand, when the total content of alkoxysiloxane, alkoxysilane, hydrolysis product thereof, and dehydration condensate thereof is 60 vol% or more, soft magnetic powder tends to aggregate during the insulating layer forming process, and the subsequent production of a dust core Occasionally, the volume ratio of the soft magnetic powder in the dust core decreases.

  The alkoxysiloxane and water in the insulating layer forming treatment liquid cause a hydrolysis reaction shown in the chemical reaction formula (1), and the alkoxysilane and water cause a hydrolysis reaction shown in the chemical reaction formula (2).

この際、水の添加量がアルコキシシロキサン又はアルコキシシランの加水分解反応の進行度を支配する因子の一つとなる。加水分解反応は軟磁性粉の表面処理を行う上で必要である。それはシラノールのＯＨ基が軟磁性粉表面のＯ原子又はＯＨ基と相互作用が強いからである。しかしながら、加水分解反応が進みシラノール基の濃度が高くなるとシラノール基を含む有機ケイ素化合物（アルコキシシロキサン又はアルコキシシランの加水分解生成物）同士の脱水縮合反応が進行し、有機ケイ素化合物の分子量が大きくなる。その結果、処理液による軟磁性粉表面の被覆率の低下、軟磁性粉同士の凝集が発生し易くなる。これは表面処理液としては適正な状態ではない。従って、絶縁層形成処理液中のアルコキシシロキサン又はアルコキシシランに対する適正な水の添加量が必要となる。ここで、絶縁層形成処理液中の水の添加量として、化学反応式（２）に示した加水分解反応における反応当量の１／１０〜１１／１０が好ましい。

At this time, the amount of water added is one of the factors governing the progress of the hydrolysis reaction of alkoxysiloxane or alkoxysilane. The hydrolysis reaction is necessary for the surface treatment of the soft magnetic powder. This is because the OH group of silanol has a strong interaction with the O atom or OH group on the surface of the soft magnetic powder. However, if the hydrolysis reaction proceeds and the concentration of the silanol group increases, the dehydration condensation reaction between organosilicon compounds containing silanol groups (alkoxysiloxane or alkoxysilane hydrolysis products) proceeds, and the molecular weight of the organosilicon compound increases. . As a result, the coverage of the surface of the soft magnetic powder by the treatment liquid is reduced, and the soft magnetic powder is easily aggregated. This is not a proper state as a surface treatment liquid. Therefore, an appropriate amount of water added to the alkoxysiloxane or alkoxysilane in the insulating layer forming treatment liquid is required. Here, the addition amount of water in the insulating layer forming treatment liquid is preferably 1/10 to 11/10 of the reaction equivalent in the hydrolysis reaction shown in the chemical reaction formula (2).

  When the amount of water added is 1/10 or less of the reaction equivalent in the hydrolysis reaction shown in the chemical reaction formula (2), the concentration of silanol groups in the organosilicon compound is low. It has a low effect and it is difficult to properly insulate the soft magnetic powder. On the other hand, when the amount of water added is 11/10 or more of the reaction equivalent in the hydrolysis reaction shown in the chemical reaction formula (2), the molecular weight of the organosilicon compound increases, so the coverage of the surface of the soft magnetic powder by the treatment liquid Decrease and aggregation of soft magnetic powders easily occur.

  The addition amount of the insulating layer forming treatment liquid is desirably 25 to 200 ml per 1 kg of the soft magnetic powder. If the amount exceeds 200 ml, the insulation coating on the surface of the soft magnetic powder becomes too thick, and the soft magnetic powder aggregates. This facilitates a decrease in magnetic flux density or an increase in hysteresis loss during the production of the dust core. On the other hand, when the amount is less than 25 ml, the insulating property is poor, and a portion where the soft magnetic powder does not get wet with the treatment liquid is generated, resulting in an increase in eddy current loss in the magnetic core.

  The soft magnetic powder may be pure iron, Fe-Si alloy, Fe-Al alloy, permalloy, sendust, or other iron-based alloy powder. However, pure magnetic iron has high magnetic flux density, good formability, and low price. Is desirable.

[Examples] The present invention will be specifically described based on examples.
[Example 1]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 2.5 ml, water 0.48 ml, dehydrated methanol 47.5 ml and 0.025 ml of dibutyltin dilaurate were mixed and a solution was used that was allowed to stand at a temperature of 25 ° C. overnight.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 40 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

  As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, in the heat treatment at 900 ° C. or less, the eddy current loss of the test piece is a constant value, so there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to heat treatment at 600 to 900 ° C. was good in terms of reducing the iron loss.

［実施例２］
軟磁性粉として平均粒径が５８μｍの鉄粉を用いた。絶縁層形成処理液にはＣＨ_３Ｏ−（Ｓｉ（ＣＨ_３Ｏ）_２−Ｏ）_ｍ−ＣＨ_３（ｍは３〜５、平均は４）を２５ｍｌ、水４．８ｍｌ、脱水メチルアルコール２０．２ｍｌ、ジラウリン酸ジブチル錫０．０２５ｍｌを混合し、１昼夜２５℃の温度で放置した溶液を用いた。
（１）鉄粉１ｋｇに対し、５０ｍｌの絶縁層形成処理液を添加し、攪拌した。その処理磁粉に対し、真空中で攪拌しながら１５０℃、１時間の熱処理を行った。尚、平均絶縁被膜厚さは５００ｎｍであった。
（２）（１）で作製した処理鉄粉を成形型に充填し、圧粉磁心の密度比が９５％になるように、７〜２０ｔ／ｃｍ^２の圧力で縦２０ｍｍ、横３０ｍｍ、厚さ５ｍｍの試験片を得た。
（３）（２）で作製した試験片について４００から１０００℃の熱処理を不活性雰囲気中で２時間実施した。

[Example 2]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. As the insulating layer forming treatment liquid, 25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, the average is 4), 4.8 ml of water, and dehydrated methyl alcohol 20. 2 ml and 0.025 ml of dibutyltin dilaurate were mixed, and a solution which was allowed to stand at a temperature of 25 ° C. overnight was used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 500 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, since the eddy current loss of the test piece is a constant value at a heat treatment of 1000 ° C. or less, there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to heat treatment at 600 to 1000 ° C. was good in terms of reducing the iron loss.
[Example 3]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. 0.25 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 0.048 ml of water, dehydrated methyl alcohol A solution obtained by mixing 49.8 ml and 0.025 ml of dibutyltin dilaurate and allowing to stand at a temperature of 25 ° C. overnight was used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 3 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, in the heat treatment at 900 ° C. or less, the eddy current loss of the test piece is a constant value, so there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to heat treatment at 600 to 900 ° C. was good in terms of reducing the iron loss.
[Example 4]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming treatment solution is a solution of 2.5 ml of Si (CH ₃ O) ₄ , 0.59 ml of water, 47 ml of dehydrated methyl alcohol, and 0.025 ml of dibutyltin dilaurate, and left at a temperature of 25 ° C. overnight. Was used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulating film thickness was 25 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, in the heat treatment at 600 ° C. or lower, the eddy current loss of the test piece is a constant value, so there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to the heat treatment at 600 ° C. was good in reducing the iron loss.
[Comparative Example 1]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. As the insulating layer forming treatment solution, a solution in which 1 g of phosphoric acid, 0.2 g of boric acid, 0.2 g of magnesium oxide, 0.05 g of a perfluorosurfactant, and 49 g of water were used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 40 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  Various magnetic properties were measured on the outer peripheral surface of the obtained test piece under the conditions of 1T and 400 Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 2 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tends to decrease with an increase in the heat treatment temperature, and the eddy current loss of the test piece increases with a heat treatment of 500 ° C. or higher. Therefore, the heat treatment temperature at which hysteresis loss and eddy current loss can be reduced. Cannot be found. Therefore, it was found that it was difficult to produce a test piece with reduced iron loss by the production method of this comparative example.
[Comparative Example 2]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. As the insulating layer forming treatment solution, 40 ml of CH ₃ O— (Si (CH ₃ O) ₂ —O) _m —CH ₃ (m is 3 to 5, average is 4), 7.7 ml of water, dehydrated methyl alcohol 2. 3 ml and 0.025 ml of dibutyltin dilaurate were mixed, and a solution which was allowed to stand at a temperature of 25 ° C. overnight was used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The iron powder was agglomerated and the average insulating film was observed to be thicker than 1000 nm.
(2) The treated iron powder prepared in (1) was filled into a mold and an attempt was made to form a dust core with a pressure of 20 t / cm ² , but only a test piece with a density ratio of 76% was obtained. Further, the test piece was poor in mechanical strength, and it was difficult to evaluate various magnetic properties.

Therefore, when the volume fraction of the hydrolysis product of the alkoxysiloxane in the insulating layer forming treatment liquid and the total dehydrated condensate thereof is 70 vol% or more as in this comparative example, the degree of aggregation of the surface iron powder is large, and the pressure It was found that it was difficult to produce a test piece having a powder magnetic core density ratio of 95% or more.
[Comparative Example 3]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 0.025 ml, water 0.0048Ml, dehydrated methanol A solution which was mixed with 50 ml and 0.025 ml of dibutyltin dilaurate and allowed to stand at a temperature of 25 ° C. overnight was used.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was less than 1 nm, which was difficult to observe.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 2 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tends to decrease as the heat treatment temperature increases, and the eddy current loss of the test piece increases with heat treatment at 400 ° C. or higher, so that the heat treatment temperature at which hysteresis loss and eddy current loss can be reduced. Cannot be found. Therefore, it was found that when the insulation film thickness on the iron powder surface was less than 1 nm as in this comparative example, it was difficult to suppress an increase in eddy current loss, and it was difficult to produce a test piece with reduced iron loss. .
[Example 5]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 2.5 ml, water 0.048 ml, dehydrated methanol 47.5 ml and 0.025 ml of dibutyltin dilaurate were mixed and a solution was used that was allowed to stand at a temperature of 25 ° C. overnight.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 20 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

  As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, in the heat treatment at 900 ° C. or less, the eddy current loss of the test piece is a constant value, so there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to heat treatment at 600 to 900 ° C. was good in terms of reducing the iron loss. Table 2 shows the characteristics of the green compact using the magnetic powder obtained in the comparative example.

［実施例６］
軟磁性粉として平均粒径が５８μｍの鉄粉を用いた。絶縁層形成処理液にはＣＨ_３Ｏ−（Ｓｉ（ＣＨ_３Ｏ）_２−Ｏ）_ｍ−ＣＨ_３（ｍは３〜５、平均は４）を２．５ｍｌ、水０．９６ｍｌ、脱水メチルアルコール４７．５ｍｌ、ジラウリン酸ジブチル錫０．０２５ｍｌを混合し、１昼夜２５℃の温度で放置した溶液を用いた。
（１）鉄粉１ｋｇに対し、５０ｍｌの絶縁層形成処理液を添加し、攪拌した。その処理磁粉に対し、真空中で攪拌しながら１５０℃、１時間の熱処理を行った。尚、平均絶縁被膜厚さは５０ｎｍであった。
（２）（１）で作製した処理鉄粉を成形型に充填し、圧粉磁心の密度比が９５％になるように、７〜２０ｔ／ｃｍ^２の圧力で縦２０ｍｍ、横３０ｍｍ、厚さ５ｍｍの試験片を得た。
（３）（２）で作製した試験片について４００から１０００℃の熱処理をフッ化英雰囲気中で２時間実施した。

[Example 6]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 2.5 ml, water 0.96 ml, dehydrated methanol 47.5 ml and 0.025 ml of dibutyltin dilaurate were mixed and a solution was used that was allowed to stand at a temperature of 25 ° C. overnight.
(1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulation film thickness was 50 nm.
(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.
(3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. in a fluorinated atmosphere for 2 hours.

  About the obtained test piece, various magnetic characteristics were measured on conditions of 1T and 400Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 1 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

As a result, although the release of the residual stress of the iron powder is insufficient with the heat treatment at 500 ° C. or lower, the residual stress of the iron powder is reduced with the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss can be reduced. On the other hand, the specific resistance of the test piece tended to decrease as the heat treatment temperature increased. However, in the heat treatment at 900 ° C. or less, the eddy current loss of the test piece is a constant value, so there is no problem in insulation. Therefore, it was confirmed that the test piece subjected to heat treatment at 600 to 900 ° C. was good in terms of reducing the iron loss.
Example 7
FIG. 5 shows a cross-sectional view of a permanent magnet motor serving as a hollow shaft of the present invention. In the figure, 101 is a rotor back yoke core (a powder magnetic core molded body), 102 is a rotor magnet, 103 is a shaft, 104 is a stator back yoke core, and 105 is a stator coil. This example is a three-phase brushless motor having 110 rotor magnetic poles and 112 stator coils. On the stator side, the stator yoke is made of the high-density powder magnetic core shown in Examples 1 to 6, and the stator side is constituted by a coil molded body that is extremely thin in the radial direction.

  The reason why a dust core is used for this stator is that this motor has multiple poles and is essential for reducing the eddy current generated by the rotating magnetic field. The rotor side is configured by molding a powder material, and the molded body has a bond magnet part mainly composed of a binder and magnet powder, and a soft magnetic part mainly composed of a binder and soft magnetic powder, A rotor of a permanent magnet type formed using compression molding means, wherein the bonded magnet portion has a rotor structure in which at least one surface of a magnetic pole is mechanically coupled to the soft magnetic portion. This is to solve the problem. Also, the bonded magnet is manufactured by temporary molding for each segment, and anisotropy is imparted at the time of temporary molding, and the temporary molded body to which the anisotropy is imparted is formed by a main molding as a rotor having a plurality of poles. After obtaining the rotor by molding, the motor rotor is structured to be magnetized by a magnetizing magnetic field.

  FIG. 6 shows a method for temporarily forming the rotor magnet. In the figure, 108 is a magnet powder, 109 is a binder (resin), 111 is a temporary mold (die), 112 is a magnetic field generating coil, 113 is a temporary mold (punch), and 115 is a power source for the coil. FIG. 6A shows a mixing step of magnetic powder and binder resin, and FIG. 6B shows a forming step of the green compact.

  The temporary molding of the magnet is performed using a mold capable of magnetic field orientation. A material composed of magnet powder and thermoplastic or thermosetting binder is blended in an appropriate blending amount capable of obtaining the required magnetic properties, filled in a mold, compression molding, injection molding, etc. It shape | molds using the means of. At that time, the magnetic field of the magnet can be oriented with high accuracy by performing molding while energizing the magnetic field orientation coil disposed in the mold. Next, the temporary molded body having a high magnetic field orientation is integrally formed (mainly formed) with the dust core yoke.

  FIG. 7 shows an image of the main molding. In the figure, 101a is a dust core material, 102a is a magnet temporary molded body, 103 is a shaft, and 121 is a main mold (lower mold).

  FIG. 8 shows a compression mold structure. In the figure, 121 is a main mold (lower mold), 122 is a main mold (core), 123 is a main mold (upper plate), 124 is a main mold (shaft pressing plate), and 125 is A main molding die (first punch) 126 is a main molding die (second punch).

  FIG. 9 shows the positional relationship of the mold in the compression molding state. The same reference numerals as those in FIG. 8 have the same meaning. FIG. 9A shows a molding process, FIG. 9B shows a perspective view of a rotor manufactured according to the present invention, and FIG. 9C is a diagram for explaining a combined state of dust particles.

  First, the shaft 103, the powder magnetic core material powder 101a, and the bonded magnet temporary molded body 102a are respectively disposed in necessary positions in the mold. At this time, the temporary molded body has a dimensional relationship in which it can be easily arranged with a sufficient gap in the circumferential direction, and is arranged neatly. The shaft has an outer diameter portion held by the lower mold 121 and an inner diameter held by the core 122. The powder magnetic core material powder 101a is disposed between the shaft 103 and the magnet, and is measured and inserted in such an amount that a predetermined density is obtained after molding.

  The shaft is fixed in the axial direction by the presser plate 124 from above, and the first punch 125 and the second punch 126 that move up and down independently of the upper punch respectively transmit the compression force. In the example, a structure for transmitting a compressive force from the upper plate 23 via a spring is shown. This structure may be an independent compression mechanism. When the upper plate is lowered by a compression drive source such as a press, a pressing force corresponding to the amount of spring deflection is applied to the core and the second punch 126 by the spring force. The first punch is directly coupled to the upper plate, transmits the compressive stress of the upper plate directly as the compression molding force of the dust core, and performs compression at the required size. At that time, it is assumed that a sufficient compressive force is also applied to the second plate, and compression is performed up to a dimensional relationship that reduces the axial dimension of the original temporary molded body. The positional relationship of the punches after compression is as shown in FIG. 9, and the dust core yoke 1 and the bonded magnet molded body 2 are integrally molded (referred to as two-color molding) with the shaft inserted into the mold. .

  FIG. 9B shows a perspective view of the molded body taken out from the mold. A molded body in which the shaft 103, the dust core yoke portion 101, and the bonded magnet molded body 102 are firmly bonded can be obtained. FIG. 9C shows a state in which the bonding portion is viewed microscopically. The magnetic powder of the powder magnetic core powder and the magnet pre-molded body is entangled between the powder particles by the plastic deformation during mechanical compression molding, in addition to the bonding effect of the binder (resin material) on the bonding surface. And the mechanical strength of the bonding surface can be increased.

  Conventionally, when bonding sintered rare earth ring magnets obtained by sintering, segment magnets or bonded magnets obtained by injection molding to the shaft by adhesion, surface side protection with glass, carbon fiber binding tape, etc. is required However, according to this method, it is possible to obtain a tensile strength (40 to 60 MPa) that does not require protection. This makes it possible to obtain a rotor that does not require surface-side protection with glass, carbon fiber-containing bind tape, or the like.

  FIG. 11 shows a structural example of a hollow shaft coreless motor employing this rotor structure. First, on the stator side, a very thin coil is arranged circumferentially on a ring-shaped back yoke using a silicon steel sheet laminate, a dust core, or the like. The coil and core are integrated and fixed by means of molding or adhesion so that the coil does not move by electromagnetic force. On the rotor side, a rotor with very good accuracy such as diameter, axial direction and concentricity is obtained by the above-described two-color molding. At this time, the mechanical gap size between the stator and the rotor can be designed in consideration of a small assembly tolerance.

  Since this rotor magnet is a rare earth bonded magnet, the maximum energy product of the magnet is smaller than that of a sintered rare earth magnet. For this reason, it is desirable to design the effective induced voltage to be large by increasing the outer diameter portion of the magnet as much as possible. For this reason, since the inner diameter portion becomes an unnecessary portion, the inner diameter of the shaft 103 is designed to be hollow as illustrated. A motor structure obtained by assembling these stator and rotor is shown in FIG. The stator core is held by a housing, and end brackets (bearing holding portions) are disposed at both ends of the housing by inlay portions. The end bracket has a structure in which a bearing is held and a shaft is held via the bearing. As described above, since the diameter of the rotor magnet is increased and the stator coil is thinned, the shaft has a hollow structure.

  FIG. 10 shows a structural comparison between the motor of the present invention and a conventional motor. An example in which the outer diameter and the axial length of the stator are fixed and examined will be shown. (A) The figure shows a hollow shaft motor provided with a coreless system, two-color molding rotor of the present invention. The inner diameter of the stator was 58 mm, and the outer diameter of the rotor was 57.2 mm. The gap size of 0.4 mm is a gap size that can be sufficiently achieved even if the tolerance of the magnet surface size from the shaft by two-color molding is taken into consideration. The residual magnetic flux density of the magnet was Br = 0.88T, and the magnet was manufactured by two-color molding with anisotropy in the direction shown in the drawing.

  FIG. 2 (b) shows a conventional slotted core motor. The inner diameter of the stator was 34.8 mm, the outer diameter of the rotor was 34 mm, and the gap dimension was 0.4 mm, which was the same as that of the structure (a). The residual magnetic flux density of the magnet was Br = 1.2T, and a thickness of 3 mm was adopted for the sintered ring magnet. In the case of a small-diameter ring magnet, a bonding area of about 0.1 mm is provided on the inner diameter side, and sufficient adhesive strength can be obtained by bonding with a highly viscous adhesive. Therefore, the gap should be used unless it is used under extremely severe temperature conditions. Since 0.4 mm may be sufficient, it was set to the same extent as the gap size of the present invention. This structure has many structures as a conventional motor, but does not become a hollow shaft.

  (C) The structure in the case of using a sintered rare earth radial ring magnet by a coreless system is shown in the figure. In this case, since the torque transmission diameter is large, the thickness of the magnet is increased to 4 mm. Increasing the thickness of the magnet increases the amount of magnetic flux and increases the mechanical strength, but it is difficult to obtain a highly accurate radial orientation during molding of the magnet, so the residual magnetic flux density was set to 1.05 T. In addition, in the case of having radial anisotropy, the coefficient of thermal expansion is remarkably different between the radial direction and the circumferential direction. Therefore, it is essential to ensure the strength of the magnet in this structure having a large diameter. For this reason, a bonding area 103 on the inner diameter side at the time of assembling the magnet and a surface protection area made of a thin non-magnetic material such as glass on the surface of the magnet, a binding tape containing carbon fiber, or stainless steel are required. For this reason, the space | gap dimension seen from the magnetic circuit becomes large compared with the structure of (a), and when the stator inner diameter is the same 58 mm, the rotor outer diameter must be 56 mm.

  The motor having the two-color molded rotor of the present embodiment can have a hollow shaft structure while obtaining a large output even though the residual magnetic flux density of the magnet is small.

In the present embodiment, an example of an internal rotation type motor is shown, but the same result is obtained even in an external rotation type motor having a rotor on the outside.
Example 8
Next, an eighth embodiment will be described. The powder magnetic core and the magnet of the hollow shaft permanent magnet motor of the present invention have a higher molding density, and the better the insulating properties, the better the motor characteristics. In order to improve the molding density, it is necessary to increase the pressure for press molding. However, if the pressure is too high, the insulating coating on the surface of the magnetic powder is destroyed and eddy current loss increases. If the insulating coating is set thicker for insulation protection, the magnet's energy product decreases and the permeability decreases due to insufficient density, and the motor characteristics are remarkably deteriorated. In order to satisfy these contradictory characteristics at the same time, a method of strengthening the magnetic powder coating can be considered.

As a method of forming an insulating film, a plate-like fluorine compound is formed at the grain boundary to increase the interface between the fluorine compound and the main phase, to reduce the thickness of the fluorine compound, or to change the fluorine compound to a ferromagnetic phase. Can be mentioned. In the former, it is effective to adopt a method of forming a plate shape or a flat shape when forming a powder of the fluorine compound. In the case of NdF ₃ , NdF ₃ powder having an average particle size of 0.2 μm and NdFeB alloy powder are mixed using an automatic mortar in the case of NdF ₃ , and there is no description about the shape of fluoride. The shape of the fluoride after sintering is a lump.

In contrast, an example of this method is that the fluoride powder is layered after magnet formation. In order to make the shape of the fluorine compound powder into a layer after the magnet is formed, the powder shape of the fluorine compound used is made into a plate shape. An example of such a technique is dissolving and quenching fluoride to form a plate. After melting at a melting temperature of about 2000 ° C. under vacuum, a rapid cooling rate is 10 ⁵ ° C./sec. By rapidly cooling, a plate shape having a thickness of 10 μm or less and an aspect ratio of 2 or more can be obtained.

  In addition to using such plate-like powder, there is also a method in which the main phase and the fluorine compound are heated and pressurized so that the fluorine compound is layered along the grain boundary. If the fluorine compound is formed into a layer after molding, the interfacial area between the fluorine compound and the main phase is increased rather than being agglomerated or granulated, and is formed along the grain boundary after molding. When the fluoride is layered, the magnetic property is improved by at least the fluoride mixed amount rather than the bulk.

  In addition, regarding the ferromagnetization of the fluorine compound, Fe or Co is added to the fluorine compound and a powder or ribbon is formed through a rapid cooling process. Fluorine compounds are paramagnetic and have a low magnetization at room temperature. Therefore, if fluoride is mixed with the main phase, the residual magnetic flux density decreases in proportion to the mixing amount. The decrease in residual magnetic flux density leads to a significant decrease in energy product. Therefore, in a magnetic circuit designed with a high magnetic flux density, it was difficult to form a conventional magnet containing a fluorine compound. However, if the fluorine compound can be made ferromagnetized, even if the addition amount of the fluorine compound is the same, the saturation magnetic flux The values of density and residual magnetic flux density can be increased by adding ferromagnetic fluoride. Even if the fluorine compound exhibits ferromagnetism, the coercivity or squareness of the main phase is adversely affected unless the coercivity of the fluorine compound itself is increased.

  In order to increase the residual magnetic flux density by securing the squareness while maintaining the main phase coercive force, it is necessary to increase the coercive force of the fluorine compound. By setting the coercive force of the fluorine compound itself to 1 kOe or more, it is possible to secure the main phase coercive force and the squareness and reduce the decrease in the residual magnetic flux density. In order to form such a fluorine compound having a coercive force, a technique of dissolving and quenching the fluorine compound and the ferromagnetic material is applied. There are single roll method and twin roll method for rapid cooling.

Specific production examples are shown below. The NdFeB alloy is a powder having a particle size of about 100 μm that has been subjected to hydrodehydrogenation, and the coercive force of this powder is 16 kOe. The fluorine compound mixed with the NdFeB powder is NdF ₃ . The NdF ₃ raw material powder is quenched using a quenching device to form a plate-like or ribbon-like powder. The raw material powder 102 is melted in an inert gas atmosphere 101 by arc melting with a tungsten electrode 103, and the shutter 107 is opened from the nozzle 104 to spray NdF ₃ dissolved on the roll 105. Ar gas is used as the inert gas, Cu or Fe-based material is used as the single roll 105, and the single roll rotated at 500 to 5000 rpm is pressurized with Ar gas and sprayed using a differential pressure.

NdF3 powder obtained becomes plate-like, and mixed so that the NdF ₃ powder and NdFeB powder NdF ₃ of about 10 wt%. This mixed powder was oriented and compressed with a magnetic field of 10 kOe, and heat compression molded in Ar gas. The molding conditions were a heating temperature of 700 ° C., a compression pressure of 3 to 5 t / cm ² , and a 7 mm × 7 mm × 5 mm anisotropic magnet was produced. The density of the produced compacts was 7.4 g / cm ³ or more. A pulse magnetic field of 30 kOe or more was applied in the anisotropic direction of the molded anisotropic magnet, and the demagnetization curve was measured at 20 ° C. The NdF ₃ thickness is an average thickness of the NdF ₃ layer at the grain boundary of the main phase Nd ₂ Fe ₁₄ B particles. The NdF ₃ thickness varies depending on the NdF ₃ powder forming conditions, the heat compression molding conditions, the NdFeB powder shape, and the like. In order to change the NdF ₃ thickness, the roll rotation speed at the time of NdF ₃ powder production is changed from 500 to 5000 rpm, and the pulverized powder is further classified by a mesh or the like.

The NdF ₃ thickness can be reduced as the rotational speed is higher and the compression molding pressure is higher. When NdF ₃ is increased from 0.01 μm, the values of Br (residual magnetic flux density), iHc (coercive force) and Bhmax (energy product) tend to increase. When the NdF3 thickness is in the range of 0.1 to 10 μm, iHc increases remarkably and Br also increases. The coercive force increases due to the presence of NdF ₃ at the interface, but the decrease in thickness is presumed to be due to the weak magnetic coupling between particles because NdF ₃ is a paramagnetic substance. Br is increased because the magnetic flux density in a low magnetic field is increased.

As a result of measuring the temperature dependency of the coercive force of the magnet having the NdF ₃ thickness of 1.0 μm by heating in the atmosphere, the temperature coefficient of the coercive force is 5.0% / ° C. in the case of the NdF ₃ additive-free magnet. Increasing the thickness of NdF ₃ reduces the temperature coefficient of coercivity. The effect is that the NdF ₃ thickness is 0.1 μm to 10 μm, and the temperature coefficient of the coercive force is 3.4% / ° C. at the minimum. It is presumed that this is related to the fact that NdF ₃ prevents oxidation of the main phase and the stabilization of the magnetic domain by increasing the coercive force. The result that the average coverage with respect to the main phase of the fluoride is about 50% indicates that when the NdF ₃ thickness is 0.1-10 μm, the coverage is changed when the coverage is changed. The coverage is related to parameters and conditions such as the mixed state of fluoride powder, the particle size of fluoride powder, the particle size of NdFeB powder, the shape of NdFeB powder, the orientation magnetic field, the pressure during orientation, and the heating conditions. As the coverage increases, the coercivity tends to increase.

By creating a rotor for a hollow shaft motor using the magnetic powder created by the above method, the rotor is less susceptible to thermal demagnetization, and by applying a hard magnetic material with a low coercivity temperature coefficient, it is strong against reverse magnetic fields. The temperature dependence of the induced voltage is small, and a stable output up to a high temperature can be obtained.
Example 9
Next, a system using the hollow shaft motor of the present invention will be described. FIG. 12 shows an example of a system that can be expected to be effective by using the hollow shaft motor of the present invention. FIG. 9A is a diagram showing a model of a steering apparatus for an automobile. Conventionally, power steering devices for automobiles have been hydraulically driven. However, motors have been improved in performance, and systems that are electrically driven have begun to appear. The motor that drives the steering device rotates so as to assist when a person operates the steering wheel, and generates a driving force to change the direction of the tire. However, it is necessary to reduce the loss torque of the motor itself in order to remove the weight when the motor is turned by operating the motor handle.

For this reason, since the motor which does not have a core can eliminate the hysteresis loss of a core, the objective can be achieved. In addition, since the efficiency in a certain output region can be higher than that in the case of using a silicon steel plate, it can be said to be an optimal system for applications in which electric power is supplied from a battery such as an automobile and fuel consumption must be taken into consideration. Further, since no core is required, the space factor of the winding can be improved, and the physique (volume) of the motor can be reduced. Also, as shown in (b), the mechanical parts such as the planetary gear 143 and the ball screw mechanism 144 shown in (c) shown in FIG. Mounting in an in-vehicle space becomes easy.
[Comparative Example 4]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 2.5 ml, water 1.92 ml, dehydrated methanol 47.5 ml and 0.025 ml of dibutyltin dilaurate were mixed and a solution was used that was allowed to stand at a temperature of 25 ° C. overnight.

  (1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulating film thickness was 80 nm, but aggregation was observed in the iron powder.

(2) The treated iron powder prepared in (1) was filled in a mold and an attempt was made to form a dust core with a pressure of 20 t / cm ² , but only a test piece with a density ratio of 89% was obtained. Further, the test piece was poor in mechanical strength, and it was difficult to evaluate various magnetic properties.

Therefore, when the amount of water added is 11/10 or more of the hydrolysis reaction equivalent with respect to the total amount of alkoxysiloxane as in this comparative example, the degree of aggregation of the magnetic iron powder is large, and the density ratio of the dust core is It was found that it was difficult to produce a test piece of 95% or more.
[Comparative Example 5]
Iron powder having an average particle size of 58 μm was used as the soft magnetic powder. The insulating layer forming solution _{CH 3 O- (Si (CH 3} O) 2 -O) m -CH 3 (m is 3-5, average 4) 2.5 ml, water 0.0096Ml, dehydrated methanol 47.5 ml and 0.025 ml of dibutyltin dilaurate were mixed and a solution was used that was allowed to stand at a temperature of 25 ° C. overnight.

  (1) 50 ml of an insulating layer forming treatment liquid was added to 1 kg of iron powder and stirred. The treated magnetic powder was heat treated at 150 ° C. for 1 hour with stirring in vacuum. The average insulating film thickness was 15 nm, and many cracks were observed in the insulating film.

(2) The treated iron powder produced in (1) is filled into a mold, and the density ratio of the powder magnetic core is 95%. The pressure is 7 to 20 t / cm ² and the length is 20 mm, the width is 30 mm, and the thickness is A 5 mm test piece was obtained.

  (3) The test piece prepared in (2) was subjected to heat treatment at 400 to 1000 ° C. for 2 hours in an inert atmosphere.

  Various magnetic properties were measured on the outer peripheral surface of the obtained test piece under the conditions of 1T and 400 Hz. Note that the outer peripheral surface of the test piece includes a portion that is in contact with the mold during molding and receives the strain due to pressurization and has the highest residual stress. Table 2 shows the measurement results of the heat treatment temperature, residual stress and magnetic properties of each specimen.

  As a result, although the release of the residual stress of the iron powder was incomplete in the heat treatment at 500 ° C. or lower, the residual stress of the iron powder was reduced in the heat treatment at 600 ° C. or higher, and as a result, the hysteresis loss could be reduced. On the other hand, the specific resistance of the test piece tends to decrease as the heat treatment temperature increases, and the eddy current loss of the test piece increases with heat treatment at 600 ° C. or higher, so that the heat treatment temperature at which hysteresis loss and eddy current loss can be reduced. Cannot be found. Therefore, as in this comparative example, when the amount of water added is less than 1/10 of the hydrolysis reaction equivalent with respect to the total amount of alkoxysiloxane, the quality of the insulating coating on the iron powder surface is degraded and the increase in eddy current loss is suppressed. It was difficult to produce a test piece with reduced iron loss.

  The present invention is capable of heat treatment while suppressing eddy current loss with respect to deterioration of magnetic characteristics during molding, core parts having small hysteresis loss or eddy current loss, motor cores and diesel engines that require high magnetic flux density, and It is used as a solenoid core (fixed iron core) for a solenoid valve and a plunger incorporated in an electronically controlled fuel injection device of a gasoline engine, and a core component for various other actuators.

The cross-sectional schematic diagram of the magnetic powder of this invention. The cross-sectional schematic diagram of the magnetic powder after annealing of this invention. The cross-sectional schematic diagram of a well-known magnetic powder. The cross-sectional schematic diagram of the powder magnetic core by this invention. It is sectional drawing of the permanent magnet motor used as the hollow shaft of this invention. It is drawing which shows the temporary forming method of the rotor magnet of this invention. It is drawing explaining the image of 2 color molding of this invention. It is drawing which shows the compression molding die structure of the 2 color molding of this invention. It is drawing which shows the metal mold | position positional relationship at the time of the compression molding of the two-color molding of this invention. 2 is a structural comparison between the motor of the present invention and a conventional motor. The structural example of the hollow shaft motor which employ | adopted the 2 color shaping | molding rotor structure of this invention is shown. It is explanatory drawing which showed the system which uses the motor of this invention for the power steering system for motor vehicles.

Explanation of symbols

1,3 ... soft magnetic powder, 2,2 '... oxide film, 4 ... oxide particles, 5 ...軟治of powder, 6 ... SiO ₂ treatment film, 101 ... rotor back yoke core (powder core formed body) , 101a ... dust core material, 102 ... rotor magnet, 102a ... magnet temporary molding, 103 ... shaft, 104 ... stator back yoke core, 105 ... stator coil, 106 ... stator core, 108 ... magnet powder, 109 ... Binder (resin), 111 ... Temporary mold (die), 112 ... Coil for generating magnetic field, 113 ... Temporary mold (punch), 121 ... Main mold (lower mold), 122 ... Main mold Mold (core), 123 ... Main mold (upper plate), 124 ... Main mold (shaft retainer plate), 125 ... Main mold (first punch), 126 ... Main mold (second) Punch), 131 ... adhesive layer, 132 ... bind layer (charcoal) Fibers, glass fibers), 133 ... molding material, 134 ... bearings, 135, 136 ... end bracket, 137 ... housing, 141 ... handle, 142 ... power steering motor, 143 ... planet gear, 144 ... ball screw.

Claims (23)

Pressure of magnetic powder having an insulating film formed on a surface of iron powder or an alloy powder containing iron as a main component using a treatment liquid containing at least one selected from alkoxysilane and derivatives thereof and alcohol and water A powder molded body having a density of 7.5 g / cm ³ or more, an average particle size of the magnetic powder of 30 to 200 μm, an average thickness of the insulating film of 1 to 700 nm, and a specific resistance Is a powder magnetic core characterized by having a value of 1000 μΩ · cm or more.   2. The dust core according to claim 1, wherein the insulating film has an average thickness of 30 to 200 nm.   2. The dust core according to claim 1, wherein the insulating film has an average thickness of 40 to 100 nm. A magnetic powder having an insulating film formed on a surface of an iron powder or an alloy powder containing iron as a main component by using a treatment liquid containing at least one selected from alkoxysilane and derivatives thereof and alcohol and water. When the green powder having a mean particle size of 30 to 200 μm, a mean thickness of the insulating film of 1 to 700 nm and a density of 7.5 g / cm ³ is produced. A magnetic powder characterized by being capable of giving a characteristic that the specific resistance is 1000 μΩ · cm or more.   The magnetic powder according to claim 4, wherein the magnetic powder has an average particle size of 40 to 100 μm.   An insulating layer forming treatment liquid for soft magnetic powder for dust cores, comprising at least one selected from alkoxysilanes and derivatives thereof, alcohol and water.   Furthermore, the catalyst for hydrolysis is contained, The insulating-layer formation processing liquid of the soft-magnetic powder for dust cores of Claim 6 characterized by the above-mentioned.   The insulating layer forming treatment liquid for soft magnetic powder for dust core according to claim 7, wherein the hydrolysis catalyst is a neutral catalyst.   The said neutral catalyst is a tin catalyst, The insulating-layer formation processing liquid of the soft-magnetic powder for dust cores of Claim 8 characterized by the above-mentioned.   The insulating layer forming treatment liquid for soft magnetic powder for dust core according to claim 6, wherein the derivative of alkoxysilane is any one of its hydrolysis product, its dehydration condensate and alkoxysiloxane.   The volume fraction of said alkoxysilane and its derivative is 0.2-60 vol% of a processing liquid, The insulating layer formation processing liquid of the soft magnetic powder for dust cores of Claim 6 characterized by the above-mentioned.   An insulating layer forming treatment liquid for soft magnetic powder for dust cores, wherein the content of water in the insulating layer forming treatment liquid is 1/10 to 11/10 of the hydrolysis reaction equivalent.   In the method for forming an insulating layer of a soft magnetic powder for a powder magnetic core, wherein an insulating layer is formed on the surface of the soft magnetic powder, the insulating layer forming treatment liquid contains at least one of alkoxysilane and its derivatives, alcohol and water, and further necessary A dust core comprising a catalyst for hydrolysis, and an insulating layer forming treatment liquid is mixed with the soft magnetic powder, and an insulating layer having an average thickness of 1 to 700 nm is formed by heat treatment at a predetermined temperature. For forming an insulating layer of soft magnetic powder for use.   The method for forming an insulating layer according to claim 13, wherein the hydrolytic catalyst comprises a neutral catalyst as a soft magnetic powder for a dust core.   The method for forming an insulating layer of a soft magnetic powder for a dust core according to claim 13, wherein the neutral catalyst is a tin catalyst.   14. The method for forming an insulating layer of a soft magnetic powder for a dust core according to claim 13, wherein the volume fraction of the alkoxysilane and its derivative sum in the insulating layer forming treatment liquid is 0.2 to 60 vol%.   A motor comprising a stator and a rotor, wherein the dust core according to claim 1 is used for the rotor.   In a hollow shaft motor having air core coils arranged on the circumference as a stator, the rotor is composed of the dust core and the magnet according to claim 1, and the dust core and the magnet are compression-molded simultaneously. A motor characterized by adopting a molded product obtained by this.   19. The motor according to claim 18, wherein the magnet, the dust core, and the shaft are integrally molded by simultaneously applying pressure in the compression direction in the axial direction to at least the dust core or the magnet portion in the same mold. A motor characterized by having a child.   19. The motor according to claim 18, wherein the magnet is a powder magnetic core, a powder magnetic core, or a shaft using a magnet temporary molded body preliminarily molded in order to form a magnet magnetization direction and obtain a predetermined initial shape. A motor characterized by comprising a rotor that is integrally molded with the rotor.   19. The motor according to claim 18, wherein the magnet is provisionally formed at the time of provisional molding so that one magnet is divided into a plurality of provisional compacts, and the magnetization orientation direction thereof is a one-point concentration type magnetic field orientation. A motor comprising a rotor formed by integrally molding a dust core, a dust core, and a shaft using a magnet temporary molded body.   The motor according to claim 18, wherein the rotor is not reinforced with glass or carbon fiber binding material as a mechanical strength member on the surface of the rotor.   19. The motor according to claim 18, wherein the rotor has a portion coupled by a plastic deformation from the original shape of the powder due to compressive stress at the interface between the rotor magnet and the dust core or the shaft and the dust core. A motor characterized by comprising

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